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• ASP.NET 1.0 site error after upgrade to VS.NET 2010

  - by Keith

  Help. I installed VS.NET 2010 and now my existing ASP.NET MVC application won't run. I checked that the 1.0 version of System.Web.Mvc is still referenced but when I browse my application, I get an error like this: "Compiler Error Message: CS1579: foreach statement cannot operate on variables of type 'object' because 'object' does not contain a public definition for 'GetEnumerator'". My partial view has this declaration: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<List<ProductModel" %> //various import statements <div <% foreach (var category in Model.Categories) { % <span<%= category.Name %</span <span<%= category.Market%</span <% } % </div For what it's worth, the source view shows ViewUserControl in red and gives a tool tip reading "Cannot resolve symbol 'ViewUserControl'". My working code didn't change, the only delta is that I upgraded to VS.NET 2010 (which includes MVC 2.0); I'm sure something is not referenced correctly but I cannot figure out what's going on.

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• Using C# and gppg, how would I construct an abstract syntax tree?

  - by Rupert

  Is there a way to do this almost out-of-the-box? I could go and write a big method that would use the collected tokens to figure out which leaves should be put in which branches and in the end populate a TreeNode object, but since gppg already handled everything by using supplied regular expressions, I was wondering if there's an easier way? Even if not, any pointers as to how best to approach the problem of creating an AST would be appreciated. Apologies if I said anything silly, I'm only just beginning to play the compiler game. :)

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• v8 is too slow for my purpose

  - by Scott

  I'm working on a music visualization plugin for libvisual. It's an AVS clone -- AVS being from Winamp. Right now I have a superscope plugin. This element has 4 scripts, and "point" is run at every pixel. You can imagine that it has to be rather fast. The original libvisual avs clone had a JIT compiler that was really fast, but it had some bugs and wasn't fully implemented, so I decided to try v8. Well, v8 is too slow running the compiled script at every pixel. Is there any other script engine that would be pretty fast for this purpose?

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• Interview - Program on Computer

  - by Gilad Naor

  Spent some time searching, couldn't find exactly what I'm after. We like giving hands-on programming exercises as part of the interview process. The interviewee gets a laptop, with the editor and compiler of his choice. He or she then get a programming exercise and has about an hour to code it. Depending on the nature of the question, internet access is either allowed or forbidden. I'm looking for good general questions for a junior developer. I don't care what language they choose to program in. C++ is as good as Python or Scheme, as long as (s)he can program in it (this rules out "can you write a correct copy-constructor" style questions). I just want to see how they code, if their code is self-documenting, if they write tests, check edge-cases, etc. What kind of questions would you ask?

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• eclipse gcov plugin

  - by Taani

  I am using gcov plugin in Eclipse CDT + cygwin compiler & linker to find code coverage. I installed gcov plugin from http://svn.sourceforge.jp/svnroot/ginkgo/trunk/org.ginko.gcov.update/ location and follow the below link to get coverage of my .c file. I was able to create .gcno and .gcda files. But double clicking on those files, opens the files in eclipse editor. I could not find the gcov editor. Also I couldn't see any code coverage results in my .c file. What is the wrong with my procedure?

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• CString error, 'CString': is not a member of 'ATL::CStringT<BaseType, StringTraits>'

  - by flavour404

  Hi, I am trying to do this: #include <atlstr.h> CHAR Filename; // [sp+26Ch] [bp-110h]@1 char v31; // [sp+36Ch] [bp-10h]@1 int v32; // [sp+378h] [bp-4h]@1 GetModuleFileNameA(0, &Filename, 0x100u); CString::CString(&v31, &Filename); But I am getting the compiler error C2039:'CString': is not a member of 'ATL::CStringT' This is a non MFC based dll, but according to the docs you should be able to use CString functionality with the include #include atlstr.h how do I make it work? Thanks

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• Is it normal for C++ static initialization to appear twice in the same backtrace?

  - by Joseph Garvin

  I'm trying to debug a C++ program compiled with GCC that freezes at startup. GCC mutex protects function's static local variables, and it appears that waiting to acquire such a lock is why it freezes. How this happens is rather confusing. First module A's static initialization occurs (there are __static_init functions GCC invokes that are visible in the backtrace), which calls a function Foo(), that has a static local variable. The static local variable is an object who's constructor calls through several layers of functions, then suddenly the backtrace has a few ??'s, and then it's is in the static initialization of a second module B (the __static functions occur all over again), which then calls Foo(), but since Foo() never returned the first time the mutex on the local static variable is still set, and it locks. How can one static init trigger another? My first theory was shared libraries -- that module A would be calling some function in module B that would cause module B to load, thus triggering B's static init, but that doesn't appear to be the case. Module A doesn't use module B at all. So I have a second (and horrifying) guess. Say that: Module A uses some templated function or a function in a templated class, e.g. foo<int>::bar() Module B also uses foo<int>::bar() Module A doesn't depend on module B at all At link time, the linker has two instances of foo<int>::bar(), but this is OK because template functions are marked as weak symbols... At runtime, module A calls foo<int>::bar, and the static init of module B is triggered, even though module B doesn't depend on module A! Why? Because the linker decided to go with module B's instance of foo::bar instead of module A's instance at link time. Is this particular scenario valid? Or should one module's static init never trigger static init in another module?

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• Python script to calculate aded combinations from a dictionary

  - by dayde

  I am trying to write a script that will take a dictionary of items, each containing properties of values from 0 - 10, and add the various elements to select which combination of items achieve the desired totals. I also need the script to do this, using only items that have the same "slot" in common. For example: item_list = { 'item_1': {'slot': 'top', 'prop_a': 2, 'prop_b': 0, 'prop_c': 2, 'prop_d': 1 }, 'item_2': {'slot': 'top', 'prop_a': 5, 'prop_b': 0, 'prop_c': 1, 'prop_d':-1 }, 'item_3': {'slot': 'top', 'prop_a': 2, 'prop_b': 5, 'prop_c': 2, 'prop_d':-2 }, 'item_4': {'slot': 'mid', 'prop_a': 5, 'prop_b': 5, 'prop_c':-5, 'prop_d': 0 }, 'item_5': {'slot': 'mid', 'prop_a':10, 'prop_b': 0, 'prop_c':-5, 'prop_d': 0 }, 'item_6': {'slot': 'mid', 'prop_a':-5, 'prop_b': 2, 'prop_c': 3, 'prop_d': 5 }, 'item_7': {'slot': 'bot', 'prop_a': 1, 'prop_b': 3, 'prop_c':-4, 'prop_d': 4 }, 'item_8': {'slot': 'bot', 'prop_a': 2, 'prop_b': 2, 'prop_c': 0, 'prop_d': 0 }, 'item_9': {'slot': 'bot', 'prop_a': 3, 'prop_b': 1, 'prop_c': 4, 'prop_d':-4 }, } The script would then need to select which combinations from the "item_list" dict that using 1 item per "slot" that would achieve a desired result when added. For example, if the desired result was: 'prop_a': 3, 'prop_b': 3, 'prop_c': 8, 'prop_d': 0, the script would select 'item_2', 'item_6', and 'item_9', along with any other combination that worked. 'item_2': {'slot': 'top', 'prop_a': 5, 'prop_b': 0, 'prop_c': 1, 'prop_d':-1 } 'item_6': {'slot': 'mid', 'prop_a':-5, 'prop_b': 2, 'prop_c': 3, 'prop_d': 5 } 'item_9': {'slot': 'bot', 'prop_a': 3, 'prop_b': 1, 'prop_c': 4, 'prop_d':-4 } 'total': 'prop_a': 3, 'prop_b': 3, 'prop_c': 8, 'prop_d': 0 Any ideas how to accomplish this? It does not need to be in python, or even a thorough script, but just an explanation on how to do this in theory would be enough for me. I have tried working out looping through every combination, but that seems to very quickly get our of hand and unmanageable. The actual script will need to do this for about 1,000 items using 20 different "slots", each with 8 properties. Thanks for the help!

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• Use a "User Macro" in .vcproj RelativePath

  - by Tom Leys

  Inside .vcproj files There is a list of all source files in your project. How can we use a macro to specify the path to a source file? If we do this: <File RelativePath="$(Lib3rdParty)\Qt\qtwinmigrate-2.5-commercial\src\qmfcapp.cpp"> </File> The compiler cannot find the folder: qmfcapp.cpp c1xx : fatal error C1083: Cannot open source file: '.\$(lib3rdparty)\qt\qtwinmigrate- 2.5-commercial\src\qmfcapp.cpp': No such file or directory As you can see, our project compiles in several source files from QT. QT lives inside a folder of external libraries, and we don't want hardcode the path from our project to that folder (we have a very large solution)

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• How does c# type safety affect the garbage collection?

  - by Indeera

  I'm dealing with code that handles large buffers ( 100MB) and manipulation of these is done in unsafe blocks. I'd like to refactor these to avoid unsafe code. I'm wondering about the likely memory performance gains (positive/negative/neutral) before I embark on that. I assert that if the compiler can verify types, it could possibly generate better code and that could also mean good GC performance. Is this a valid assertion? What is your experience? Thanks.

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• How does real world login process happen in web application in Java?

  - by Nitesh Panchal

  Hello, I am very much confused regarding login process that happen in Java web application. I read many tutorials regarding jdbcRealm and JAAS. But, one thing that i don't understand is that why should i use them ? Can't i simply check directly against my database of users? and once they successfully login to the site, i store some variable in session as a flag. And probably check that session variable on all restricted pages (I mean keep a filter for restricted resources url pattern).If the flag doesn't exist simply redirect the user to login page. Is this approach correct?Does this approch sound correct? If yes, then why did all this JAAS and jdbcRealm came into existence? Secondly, I am trying to completely implement SAS(Software as service) in my web application, meaning everything is done through web services.If i use webservices, is it possible to use jdbcRealm? If not, then is it possible to use JAAS? If yes, then please show me some example which uses mySql as a database and then authenticates and authorizes. I even heard about Spring Security. But, i am confused about that too in the sense that how do i use webservice with Spring Security. Please help me. I am really very confused. I read sun's tutorials but they only keep talking about theories. For programmers to understand a simple concept, they show a 100 page theory first before they finally come to one example.

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• How does sizeof calculate the size of structures

  - by Gearoid Murphy

  I know that a char and an int are calculated as being 8 bytes on 32 bit architectures due to alignment, but I recently came across a situation where a structure with 3 shorts was reported as being 6 bytes by the sizeof operator. Code is as follows: #include <iostream> using namespace std ; struct IntAndChar { int a ; unsigned char b ; }; struct ThreeShorts { unsigned short a ; unsigned short b ; unsigned short c ; }; int main() { cout<<sizeof(IntAndChar)<<endl; // outputs '8' cout<<sizeof(ThreeShorts)<<endl; // outputs '6', I expected this to be '8' return 0 ; } Compiler : g++ (Debian 4.3.2-1.1) 4.3.2. This really puzzles me, why isn't alignment enforced for the structure containing 3 shorts?

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• C# ASP.Net The type or namespace name 'iAnywhere' could not be found

  - by Louis Russell

  Morning all, I know that this sounds like a simple referencing problem from the title this is becoming a nightmare! I have a code class that uses the "iAnywhere.Data.AsaClient.dll". This Dll is referenced in the project and in the code class I have added this dll in the Using section. Everything seems fine at build with no errors at all but when I go to run the application it comes up with the following Compilation Error: Compiler Error Message: CS0246: The type or namespace name 'iAnywhere' could not be found (are you missing a using directive or an assembly reference?) The line that the Error points to this line in the class: using iAnywhere.Data.AsaClient; I have set the dll to copy local and it makes no difference, the Dll is installed on my PC so is in the GAC, I use this Dll with many other C# projects and have no problems. I have scoured Google looking for an answer and haven't found anything that points me to an answer to my problem. Any help would be brilliant!

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• gethostbyname fails for local hostname after resuming from hibernate (Vista+7?)

  - by John

  Just wondering if anyone else has spotted this: On some user's machines running our software, occasionally the call to Win32 winsock gethostbyname fails with error code 11004. For the argument to gethostbyname, I'm passing in the result from gethostname. Now the docs say 11004 is WSANO_DATA. None of the descriptions seem to be relevant (it occurs if you pass in an IP6 address, but as I say, I'm passing in a hostname). Even more interesting is that the MSDN suggests that this combination (gethostname followed by gethostbyname) should never fail, not even if there is no IP address (in that case it would just return empty list of IPs). Here is the quote from the gethostname MSDN entry: ...it is guaranteed that the name returned will be successfully parsed by gethostbyname and WSAAsyncGetHostByName. It only ever happens after resuming from hibernate, in that short period when the network is restarting, and only on Vista/7 (well I've only seen it on Vista and 7). One theory I had was that it related to IP6. Maybe for a short period the network reports an IP6 address but not the corresponging IP4 address (I'm pretty sure that all the client machines are dual IP stack, but I could be wrong). I tried to reproduce by turning off my network card (to force no IP addresses) and couldn't reproduce. Anyone seen this before? Any ideas? John

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• Reasons to learn MSIL

  - by mannu

  Hi, Learning MSIL is fun and all that. Understanding what is going on "under the hood" can in many ways improve how you write your code performance-wise. However, the IL that is produced by the compiler is quite verbose and does not tell the whole story since JIT will optimize away a lot of the code. I, personally, have had good use of my very basic IL understanding when I've had to make a small fix in an assembly I do not have the source code for. But, I could as well have used Reflector to generate C# code. I would like to know if you've ever had good use of MSIL understanding and/or why you think it is worth learning it (except for the fun in it, of course). I'd also like to know if you think one should not learn it and why.

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• Should I use concrete Inheritance or not?

  - by Mez

  I have a project using Propel where I have three objects (potentially more in the future) Occasion Event extends Occasion Gig extends Occasion Occasion is an item that has the shared things, that will always be needed (Venue, start, end etc) With this - I want to be able to add in extra functionality, say for example, adding "Band" objects to the Gig object, or "Flyers" to an "Event" object. For this, I plan to create objects for these. However, without concrete inheritance, I have to have the foreign key point to the Occasion object - giving the (propel generated) functions for all of these extra bits to anything inherited from Occasion. I could, in theory do this without a foreign constraint, and add in functions to use the Peer or Query classes to get things related to the "Gig" or similar. Whereas with concrete inheritance, I would only have these functions in the things where they are. I think the decision here is whether I should Duck Type the objects (after all they are occasions) or whether I should just use the "Occasion" object as a "template" (only being used to search for things, like, all occasions at a venue) Thoughts? Comments?

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• Difference of two 'uint'

  - by vanslly

  When you attempt to declare an unsigned variable in C#.NET with a value outside its value range it is flagged as a compiler error, but if you produce a negative value at runtime and assign it to that variable at runtime the value wraps. uint z = -1; // Will not compile uint a = 5; uint b = 6; uint c = a - b; // Will result in uint.MaxValue Is there a good reason why unsigned variables wrap in such a situation instead of throwing an exception? Thanks.

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• FIFO implementation

  - by Narek

  While implementing a FIFO I have used the following structure: struct Node { T info_; Node* link_; Node(T info, Node* link=0): info_(info), link_(link) {} }; I think this a well known trick for lots of STL containers (for example for List). Is this a good practice? What it means for compiler when you say that Node has a member with a type of it's pointer? Is this a kind of infinite loop? And finally, if this is a bad practice, how I could implement a better FIFO. EDIT: People, this is all about implemenation. I am enough familiar with STL library, and know a plenty of containers from several libraries. Just I want to discuss with people who can gave a good implementation or a good advice.

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• std::map default value for build-in type

  - by Qifa Zhao

  Recently, I was confused by the std::map operator[] function. In the MSDN library, it says: "If the argument key value is not found, then it is inserted along with the default value of the data type." I tryed to search much more exactly explanation for this issue. For example here: std::map default value In this page, Michael Anderson said that "the default value is constructed by the default constructor(zero parameter constructor)". Now my quest comes to this:"what the default value for the build-in type?". Was it compiler related? Or is there a standard for this issue by the c++ stardard committee? I did a test on visual studio 2008 for the "int" type, and found the "int" type is construted with the value 0.

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• Expression Tree : C#

  - by nettguy

  My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally when our LINQ to SQL query compiler translates it to parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

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• In Delphi 7, why can I assign a value to a const?

  - by Blorgbeard

  I copied some Delphi code from one project to another, and found that it doesn't compile in the new project, though it did in the old one. The code looks something like this: procedure TForm1.CalculateGP(..) const Price : money = 0; begin ... Price := 1.0; ... end; So in the new project, Delphi complains that "left side cannot be assigned to" - understandable! But this code compiles in the old project. So my question is, why? Is there a compiler switch to allow consts to be reassigned? How does that even work? I thought consts were replaced by their values at compile time?

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• GCC exports decorated function name only from dll

  - by Jeff McClintock

  Hi Guys, I have a dll, it exports a function... extern "C" int __stdcall MP_GetFactory( gmpi::IMpUnknown** returnInterface ) { } I compile this with Code::Blocks GCC compiler (V3.4.5). Problem: resulting dll exports decorated function name... MP_GetFactory@4 This fails to load, should be plain old... MP_GetFactory I've researched this for about 4 hours. I think --add-stdcall-alias is the option to fix this. My Code::Blocks log shows... mingw32-g++.exe -shared -Wl,--out-implib=bin\Debug\libGainGCC.a -Wl,--dll obj\Debug\se_sdk3\mp_sdk_audio.o obj\Debug\se_sdk3\mp_sdk_common.o obj\Debug\Gain\Gain.o obj\Debug\Gain\gain.res -o bin\Debug\GainGCC.sem --add-stdcall-alias -luser32 ..so I think that's the correct option in there? But no luck. Dependancy Walker show only the decorated name being exported. I got It to kinda work by using __cdecl instead of __stdcall, the name is then exported ok, but the function corrupts the stack when called (because the caller expected the other calling convention).

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• Objective-C categories: Can I add a property for a method not in my category?

  - by Squeegy

  I want to use a category to make a method on the original class available as a property as well. Class A: @interface ClassA - (NSString*)foo; @end Class A category @interface ClassA (Properties) - (void)someCategoryMethod; @property (nonatomic, readonly) NSString *foo; @end Now when I do this, it seems to work, but it gives me warnings because I am not synthesizing the property in my category implementation. How do I tell the compiler everything is actually just fine since the original class synthesizes the property for me?

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• Would this method work to scale out SQL queries?

  - by David

  I have a database containing a single huge table. At the moment a query can take anything from 10 to 20 minutes and I need that to go down to 10 seconds. I have spent months trying different products like GridSQL. GridSQL works fine, but is using its own parser which does not have all the needed features. I have also optimized my database in various ways without getting the speedup I need. I have a theory on how one could scale out queries, meaning that I utilize several nodes to run a single query in parallel. The idea is to take an incoming SQL query and simply run it exactly like it is on all the nodes. When the results are returned to a coordinator node, the same query is run on the union of the resultsets. I realize that an aggregate function like average need to be rewritten into a count and sum to the nodes and that the coordinator divides the sum of the sums with the sum of the counts to get the average. What kinds of problems could not easily be solved using this model. I believe one issue would be the count distinct function. Edit: I am getting so many nice suggestions, but none have addressed the method.

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• CoreFoundation Lite on Linux and Android

  - by celil

  I would like to use Apple's CoreFoundation library on linux and android. The source code is available here, but there is very little documentation on how to build it on Linux. As far as I could figure out, building is done through a script called BuildCFLite. I grepped for DEPLOYMENT_TARGET ./CFUtilities.c:#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_LINUX || DEPLOYMENT_TARGET_FREEBSD and Linux seems to be supported at first site by setting -DDEPLOYMENT_TARGET_LINUX, but some of the compiler flags in that script are not available on linux, so when I try to build I get an error. Does anybody have experience building the latest version of CoreFoundation for Linux? Also what are the dependencies for building CoreFoundation? Would it be feasible to use it in the Android NDK?

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